1. Field of the Invention
This invention relates to the field of rotating toys. More specifically, this invention relates to a yo-yo device, consisting of an axle, said axle being composed of two axle-segments, each axle-segment being connected to, but capable of rotating independently of, the other axle-segment; the axle-segments may be interconnected directly or indirectly; one or more discs centrally connected to each axle-segment; a single looped string having one of its ends attached to one axle-segment, and the opposite end of said string attached to the other axle-segment; said looped string being slidably supported over some support means.
2. Description of the Prior Art
A survey of the prior art reveals various toys having combined rotational motion about a horizontal axis and a translational motion in a vertical direction. One type of such toy is commonly referred to as a yo-yo. This toy has also been referred to as a return top; prince of Wales' toy; disc; Incroyable; Bandalore; or emigrette. A conventional yo-yo consists of a single axle having two parallel positioned discs centrally connected to the axle. A string is connected to the axle between the discs at one end and is held in the user's hand at the other end. The string is wrapped around the axle by the user and then is forced downward, or allowed to fall downward. During descent of the yo-yo body, the string unwinds, providing an angular momentum to the discs. Once the string has been completely unwound, the angular momentum of the discs continues to exist, thus causing the string to be rewound around the axle in the opposite direction as it travels upward vertically toward the user's hand. In another variation of the conventional yo-yo, the string is not actually tied to the axle; rather, the axle rests in the loop of the string which is doubled back upon itself. The conventional yo-yo structure is disclosed within U.S. Pat. No. 3,263,361 to Bowden, and U.S. Pat. No. 3,256,635 to Radovan.
The conventional yo-yo as described above has achieved tremendous success in the past as an entertaining toy. Furthermore, certain modifications of that conventional yo-yo such as that disclosed within Bowden may have achieved success as entertaining toys. However, the conventional yo-yo structure has a pronounced limitation when used by inexperienced or younger operators. This limitation is apparent to even the most casual observer and resides in the difficulty of maintaining the balance or equilibrium of the toy during use. The inability of the inexperienced user to maintain this balance results in wobbling and precessional motions of the yo-yo during use. The operator loses control of the yo-yo when the balance of the toy is disturbed, thus causing the yo-yo to slow its rotational motion and thereby lose its ability to maintain vertical translational motion. When the operator loses control of the yo-yo it generally undergoes a severe precessional motion about a vertical axis, that is, it spins rapidly about a vertical axis. All yo-yos available up to the present time exhibit this precessional rotation to a pronounced extent.
My copending U.S. patent application Ser. No. 120,289 was filed Feb. 11, 1980, and my copending U.S. patent application Ser. No. 138,729 was filed Apr. 9, 1980; both of those patent applications also relate to yo-yo devices. Prior attempts at modifying the conventional yo-yo structure are also disclosed within U.S. Pat. No. 3,207,508 to Klemke and U.S. Pat. No. 3,228,140 to White. The modification of Klemke and White may provide additional temporary horizontal stability to the axle by attaching two separate strings to the yo-yo at two separate points. However, those devices make no provision for the possibility of one of the strings being wound around the axle more quickly than the other, thus resulting in tilting. That problem is considered and solved in the invention of MacCarthy, U.S. patent application Ser. No. 120,289 filed Feb. 11, 1980. Another invention by MacCarthy, described within U.S. patent application Ser. No. 138,729 filed Apr. 9, 1980 describes an alternative method for enhancing the stability of the yo-yo.
Other modifications to conventional yo-yo structure have been developed within the prior art. These modifications include the addition of metal rings to the discs of the yo-yo. Some of the modifications have been directed towards improving the stability of the yo-yo. Other modifications to the conventional yo-yo structure do not have as their primary purpose the improvement of the stability of the yo-yo, but rather the development of a toy having added versatility and function, thus requiring greater skill and manual coordination for its operation.
Accordingly, the prior art appears to be comprised of yo-yo toys of conventional structure, conventional yo-yos with slight aesthetic modifications, yo-yos whose structure has been modified with the intent of providing improved stability, and yo-yos whose conventional structure has been modified with the intent of providing additional versatility and function. The structure of the present invention removes it from being classified strictly as a conventional yo-yo. Although the present invention may be modified aesthetically to produce graphic, light and sound effects, the structural differences between the present invention and a conventional yo-yo indicate that the present invention is more than a mere modification of conventional structure intended to bring out merely aesthetic differences over a conventional yo-yo.
All previous yo-yo designs undergo precession about a vertical axis if the yo-yo is swung sideways, that is, in a direction parallel to the axis of the yo-yo. The yo-yo of the present invention is unique, and differs from all previous yo-yo designs in that the precessional rotation is either totally eliminated or vastly minimized. This property of resisting precessional motion is the single most important feature of the yo-yo device embodied in the present invention.
Although the structure of the present invention was intended to and did result in total or almost total elimination of precessional rotation, the present invention is also capable of certain increased versatility of function over a conventional yo-yo and prior modifications thereof.
In the context of this Specification the term `precessional stability of yo-yo` is intended to mean the resistance of the yo-yo to going out of control, and its ability to resist precessional rotation.
As an indication of the enhanced precessional stability inherent in the yo-yo of the present invention, the following, illustrative examples may be given:
It should first be pointed out, however, that there are two primary modes in which the yo-yo of the present invention can be operated. In one mode, where the string is wrapped around the two axle-segments in the same directions, the yo-yo possesses all of the advantages inherent in my previous invention, described within U.S. patent application Ser. No. 120,289. The alternative mode of operation is totally unique to the present invention and this special capability constitutes the primary objective which led to this invention. In this unique mode of operation, where the string is wrapped about the two axle-segments in opposite directions, the yo-yo of the present invention may be swung vigorously sideways, that is in a direction parallel to the axis of the yo-yo, without experiencing a significant precessional rotation. Accordingly, the sideways swing does not inhibit the combined rotational-translational motion of the yo-yo, and the proper functioning of the yo-yo is constantly maintained; the yo-yo simply does not go out of control since it cannot experience precessional rotation.
As a further indication of the enhanced precessional stability inherent in the yo-yo of the present invention, the user will find that after minimal practice, it is possible to sustain the combined rotational-translation motion of the yo-yo while it is simultaneously being swung in a circular or orbital manner. This combined rotational-translational-orbital motion can be continued indefinitely, during which time the yo-yo successively approaches and departs from the operator's hand, and the orientation of the stretched string in space is continually changing. The plane of the orbital motion may be changed continually without disturbing the functioning of the yo-yo, that is, the circle or orbit may occur about a horizontal axis, a vertical axis, or about any other axis; and this axis may be changed rapidly by the operator during use, without upsetting the yo-yo motion. The combined translational motion of the yo-yo along the direction of the string, toward and away from the operator's hand, and the orbital motion of the yo-yo about the operator's hand, results in a net spiralling motion of the yo-yo body. The orientation of the body of the yo-yo relative to the operator is not a critical factor during the orbital swings of the yo-yo. The yo-yo can withstand very rough treatments during operation without going out of control. This type of precessional stabilitly is totally foreign to the conventional yo-yo and all prior modifications thereof.
In addition to demonstrating precessional stability, the above examples also serve to illustrate the increased versatility of the present yo-yo. It is capable of more versatile types of motion than all other types of yo-yos. Furthermore, the combined rotational-translational-orbital motion achievable with the yo-yo of the present invention does not require a great deal of skill on the part of the yo-yo operator; the ability to operate this new yo-yo can be rapidly learned. The yo-yo device of the present invention is unique in that it totally avoids precessional problems experienced by all prior yo-yo designs.